The invention relates to alkane- and arenesulfonamides, and more particularly to a novel process for their preparation.
Synthetic methods for organosulfonamides in general, and for alkanesulfonamides in particular, are well known in the literature. Many of these methods involve treating the corresponding sulfonyl chloride with ammonia or a primary or secondary amine in the presence of an organic solvent. Such processes yield an initially crude product which is contaminated with by-products. The crude product requires purification before it may be used further.
European Patent Application 0276182 describes the preparation of C.sub.1 -C.sub.4 alkanesulfonamides using di- or monoalkoxyalkane solvents.
U.S. Pat. No. 3,300,529 describes a process for preparing N-alkyl and N,N-dialkyl-substituted ethylenesulfonamides by simultaneous dehydrochlorination and amination of .beta.-chloro-alkanesulfonyl chlorides in any reactive solvent.
U.S. Pat. No. 3,781,441 describes a process for making 4-chloro-3,5-dinitrobenzenesulfonamide from the corresponding sulfonyl chloride by reaction with ammonia in various solvents at temperatures below 10.degree. C. Here the process of the patent is concerned with avoiding displacement of the aryl chlorine by ammonia.
U.S. Pat. No. 3,574,740 describes the preparation of methanesulfonamide and its derivatives by treating methanesulfonyl chloride in C.sub.1 to C.sub.4 nitroalkane with ammonia or a primary or secondary amine. Substitution of other solvents is not suggested. As stated in this patent, the solubility of methanesulfonamide in nitroalkanes is highly temperature dependent, requiring filtration at elevated temperature to remove by-products. Processing in nitroalkanes produces discolored products. Further processing is required in the nature of hot filtrations and removal of undesired color from the product.
Czechoslovakia Patent 235,626 describes treatment of methanesulfonyl chloride in solution in toluene with gaseous ammonia followed by crystallization of the methanesulfonamide product from a toluene/ethanol mixture after concentration. Ammonium chloride is soluble in the toluene/ethanol reaction mixture to over 1% by weight concentration. The product must be isolated by crystallization from the concentrated reaction mixture to separate it from the ammonium chloride remaining in solution. This results in a drop in yield to about 90%. On a large scale, this small drop in yield can have significant economic consequences.
Treatment of methanesulfonyl chloride in benzene with anhydrous ammonia to give the desired methanesulfonamide is described in the following: Field et al., J. Am. Chem. Soc., Vol. 75, pages 934-937 (1953); Field et al., J. Am. Chem. Soc., Vol. 77, pages 170-171 (1955); Pantlitschko et al., Monatsh., Vol. 89, pages 285-87 (1958), as summarized in Chem Abstracts 53:1140i (1959); and Dutt, J. Chem. Soc., Vol. 125, pages 1463-65 (1924).
Zhur. Obschei Khim., Vol 18, pages 729-32 (1948), as summarized in Chem. Abstracts 43:120f, describes treatment of methanesulfonyl chloride in dry diethyl ether with anhydrous ammonia, followed by evaporation of solvent and extraction of the residue with benzene to obtain the methanesulfonamide product.
Benzene is a known carcinogen and, while it can be handled industrially, its use complicates any process in which it is employed.
The preparation of N-substituted alkanesulfonamides from alkanesulfonyl chlorides and amines is reported by Sacco et al., J. Am. Chem. Soc., 76, 303-305 (1985).
Chem. Abstracts 56:7116f, abstracting Sokolsku et al., Izvest. Akad Nauk S.S.S.R., Otdel Khem Nauk 1606 (1968), describes the reaction of CH.sub.3 SO.sub.2 F with (C.sub.2 H.sub.5).sub.2 NH after one day to give 96.5% CH.sub.3 SO.sub.2 N(C.sub.2 H.sub.5).sub.2.
Liquid ammonia is reacted with 1,2,4-triazol-3- sulfonylchloride to give 1,2,4-triazol-3-sulfonamide in U.S. Pat. No. 2,554,816.
The reaction of alkane- and arenesulfonyl halides with ammonia or amines is extremely exothermic. The rate at which these reactants may be contacted is therefore limited by the rate at which the heat of reaction may be removed. The release of the heat of reaction has been controlled according to the prior art, by slow addition of the reactants, resulting in a concomitantly slower production rate.
What is needed is a method for the rapid, direct synthesis of alkane- or arenesulfonamides which produces minimal by-products, and which dispenses with large volumes of solvent in the primary reaction phase.